An astonishing sea stack that's lashed by foaming sea, Dun Briste is Mayo's top natural sight. Legend attests that St Patrick drove all the vipers from Ireland onto the stack on Downpatrick Head, leaving the mainland snake-free. Try to choose a clear day for a visit to amplify the visuals. You can drive most of the way up to the sea edge, but then you'll need to walk the last 400m or so. Dun Briste is 6km northeast of Ballycastle.